From Beyonce's 'Drunk in Love' song. She pronounces 'surfboard' as 'surfbort' and people take humor from this. It is a Beyonce-ism and sounds funny so has been adopted by the Beyhive as a joke/humorous word. Has been made into t-shirts by various Beyonce fans.
"Then I fill the tub up halfway then ride it with my surfbort
"Beyonce has redefined the word surfboard to surfbort"
"I'm riding my surfbort"